Weird Super-Earths Found Orbiting Neighbor Star

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Astronomers believe they have found a second distant planet
around Fomalhaut, a bright young neighbor star, and that the
far-out world -- like its sister planet -- is shepherding and
shaping the star's ring of dust.

If confirmed, theorists have some work to do explaining how the
planet, believed to be a few times bigger than Mars, ended up 155
times as far away from its parent star as Earth is to the sun.

"We're learning a lot about planets that are close to their
stars, but that is not the full picture. We also want to know
about systems where planets are very far out. By considering
near-, far- and mid-range, we can get a complete picture of
planet formation,” University of Florida astronomer Aaron Boley
told Discovery News.

Of key interest is figuring out whether the planets formed in
place or somehow migrated out there, bumped like celestial
billiard balls after gravitational encounters with another body
or bodies closer to the star.

"Whether that can actually happen is very active area of
research," Boley said.

If Fomalhaut's planets are indeed ring shepherds, they’ve been on
the job a long time, roughly 100 million years.

"Relative to the age of the star, they must have formed quickly,"
Boley added.

The suspected planet would be the second planet found orbiting
Fomalhaut, a very bright star located about 25 light-years away
in the constellation Piscis Austrinus. Fomalhaut is twice as big
as our sun and encircled by a disk of dust 16 times wider than
the span between the sun and Earth.

The inner edge of the ring is about 135 times as far as away from
the star as Earth is to the sun.

The finding was made with a new telescope called ALMA, an acronym
for Atacama Large Millimeter/submillimeter Array. With just 15 of
its planned 66 antennas operational, astronomers already are
expecting ALMA to revolutionize millimeter-wavelength astronomy,
much like the Hubble Space Telescope transformed optical
astronomy.

"The Fomalhaut image is just the beginning. They haven't even
finished getting all of their data. This is just a sneak peak,"
astronomer Paul Kalas, with the University of California at
Berkeley, told Discovery News.

Kalas and colleagues used Hubble Space Telescope images taken in
2004 and 2006 to pinpoint a speck of light believed to be the
first direct picture of a planet in orbit around another star
system. Astronomers predicted Fomalhaut had a planet smaller than
Saturn inward of the ring after earlier observations showed the
ring's sharp inner edge.

Now, another team of astronomers based at the University of
Florida used ALMA observations to find a distinct, vertical edge
to the outer part of Fomalhaut's ring as well. Both edges are
believed to be carved by the steady and stable gravitational tugs
of planets.

"What we're really looking at is an analog to our early solar
system, an epoch when a planetary system is very dynamically
active. Comets and asteroids are everywhere. Young planets have
formed. You have impacts on the surfaces, perhaps delivering
water to terrestrial planets," Kalas said.

Astronomers plan to use ALMA to map structures in Fomalhaut's
ring and possibly see if the inner planet, known as Fomalhaut b,
has its own ring, similar to Saturn's. Other targets include Beta
Pictoris, which is believed to have a planet of its own circling
about as far as Jupiter orbits in our solar system.